I have trouble distinguishing the selected choice in most menus from all the other choices, such as the menu in the top right of the posted screenshot. Now, with the game window reduced, or with the image size reduced when posting here, the indicator is clearly visible as a brigher grey. Unfortunately, that's not the case should you try to open the image in full size, or in my case playing the game in fullscreen.
What can I do to make the colour differences more apparent?
Okay, it has been suggested that I post an answer detailing how to change the colors.txt file. It's not the solution people really want, but it is the solution available.
The first step is to find the file. It is in the data\init folder under the main dwarf fortress folder. So the path will look something like [somestuff]\Dwarf Fortress\data\init\colors.txt if you are on Windows, and something like [somestuff]/df/data/init/colors.txt if you are on Linux.
Make a backup copy of your colors.txt file. Then open the main copy (not the backup) in your favorite text editor. (NOT word processor. notepad.exe will do on Windows. I often use gedit on Linux.) You will see that it contains a number of lines that look like [ALLCAPSCOLORNAME_R:134], with an R, G, and B line for each color name. You can use these to set the red, green, and blue color values respectively for each color name. (If you need some more information about the RGB color scheme look here, or Google will have lots of results). The values must be in the range 0 to 255 inclusive. (0 and 255 are allowed, -1 and 256 aren't) 0 is minimum intensity, or none of that component. 255 is maximum intensity, or as much of that component as possible. So really bright red is specified in the file as:
[LRED_R:255]
[LRED_G:0]
[LRED_B:0]
Since you want better contrast between the highlighted and non highlighted lines in the menus you want to change the values of the appropriate colors so that they have more contrast. I will admit that I have no problem seeing them as is (so long as my monitor's brightness is turned up), so I cannot give too much help on selecting colors. I will suggest changing the the color balances some to help the eye pick out the difference. (For example decrease the blue and increase the red on one color while increasing the green on the other color in the pair.)
This process is somewhat complicated by two facts. One is that this will change the colors of all the things in the game, not just the menus. So if you change the DGRAY color values the color of all your metalsmiths and furnace workers will also change.
The second fact is that the menus do not use a consistent set of colors. You will need to change many colors to get all the menus.
The menus that I have checked so far are:
All in all I would say that making sure it's easy to differentiate between DGRAY, LGRAY and WHITE is the most important consideration. Experiment some with the colors, and when you find a set that works for you, make a backup of the new colors.txt as well, so that you can just drop it into new installs instead of having to do the whole process over.
Hopefully this is of some use even if it's not the best solution.
Interestingly enough, I've never encountered this problem and I also don't have any problem seeing that you have "Rain" selected when the image is blown up to full-size.
The easiest solution is to not play the game in fullscreen, which is what I usually do anyway (I have played the game in fullscreen before, and still haven't encountered the same issue) Of course, this isn't an ideal solution if you really prefer fullscreen.
The game has a pretty basic color palette, analogous to ANSI colors (also used in MUDs) I believe. Here is an ANSI color table. It consists of 16 colors; 8 basic colors and darker shades of those same 8 colors. I haven't gone through the game's color codes to verify that they're the exact same as ANSI codes, but I've played more than my fair share of MUDs and I can tell you that the palette definitely looks familiar. Namely, the last two colors on that table are the LGRAY and WHITE that you'd be looking at.
As Nick mentions in the comments to the OP, you can also change the color values for the LGRAY and WHITE color variables that the game uses for the menu. You mentioned having trouble distinguishing these two colors in the menu -- therefore, while it is true that you may well mess up something relating to the game interface, it sounds to me like it will help you, if anything. Seems like it would make it easier to tell gray items from white ones on the world map.
Fortunately, DF has very transparent game files that can easily be edited by the user. I say take Nick's suggestion and modify your color settings -- all you have to do to restore any bad changes is back up your original file. It's not like you can permanently break the game this way, and even if you do you can just extract your save/world file and reinstall the game.
Find an old CRT and play on that. I used to play MUD on CRT and there was a similar thing. The white vs gray was very distinct on it. When I moved to LED/LCD, I could barely tell the difference anymore.
Its an artifact of your monitor. Maybe changing contrast or brightness will help if you don't have a CRT. CRT were just superior imo. But it is possible to work out the settings on your monitor/tv thats lcd/led to make it visible. I just did that to fix mine by clicking on the computer setting in the video presets of the monitor, and it worked, although I had to turn that brightness down.
